# Trouble with Modbus Addressing within OPCUA Device Connections

**URL:** <https://forum.inductiveautomation.com/t/trouble-with-modbus-addressing-within-opcua-device-connections/114238>\
**Category:** Ignition\
**Tags:** opcua\
**Created:** [February 27, 2026, 9:12pm UTC](https://forum.inductiveautomation.com/t/trouble-with-modbus-addressing-within-opcua-device-connections/114238 "2026-02-27T21:12:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![logan.h](https://avatars.discourse-cdn.com/v4/letter/l/58f4c7/32.png) [@logan.h](https://forum.inductiveautomation.com/u/logan.h)\
**Post date:** [February 27, 2026, 9:12pm UTC](https://forum.inductiveautomation.com/t/trouble-with-modbus-addressing-within-opcua-device-connections/114238/1 "2026-02-27T21:12:52Z")

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After adding the unit (with correct IP) to the OPC Device Connections ( status is connected), I’m finding that no matter what address I put in, the quality is bad or UncertainInitialValue.

Perhaps I’m misinterpreting the manual, but my Item Path Syntax is as follows:

[OPC Connection Name]1.44867

Could my error somehow be with the connection, or is it merely my addressing syntax?

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<div class="post-metadata">

**Author:** ![ryan.white](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/ryan.white/32/73193_2.png) [@ryan.white](https://forum.inductiveautomation.com/u/ryan.white)\
**Post date:** [February 27, 2026, 9:18pm UTC](https://forum.inductiveautomation.com/t/trouble-with-modbus-addressing-within-opcua-device-connections/114238/2 "2026-02-27T21:18:49Z")

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Your modbus addressing syntax is incorrect, try `[OPC Connection Name]1.HR4867`. Ignition uses prefixes to designate the different address sets. It also allows you to tell it how to interpret multiple registers, like a float (`HRFxxxx`) or 32 bit integer (`HRIxxxx`).

> **[Modbus Specific Addressing​ - Modbus Addressing | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.1/ignition-modules/opc-ua/opc-ua-drivers/modbus/modbus-addressing#modbus-specific-addressing)**
>
> Modbus doesn't support tag browsing, this means you cannot view the Tags in the Connected Devices window in the Designer or from the OPC Connections \> Quick Client in the Config section of the Gateway. | Manually Addressing a Modbus Device

Depending on your device you may also need to mess around with the `Zero Based Addressing` and `Reverse Word Order` settings in the device connection config to get the correct values.